This invention relates in general to photographic film and paper developing and processing, and more particularly to a portable apparatus for processing sensitized materials such as rolls and sheets of photographic, graphic arts, and medical films and paper.
Many types of processors are available for developing sensitized materials such as film and paper by transporting the material through chemical and wash solutions and then through a drying compartment to dry the developed material. In order to provide consistent and high quality development of the film or other material, it is important that the chemical solutions remain at a constant temperature and be continually circulated to bring fresh solution into contact with the material as it is being developed. The chemical solutions must also be continually filtered and periodically replenished with fresh chemicals.
Conventional processors typically house the circulation pumps, filters, heat exchangers and replenishing pumps which are needed to maintain the activity of the chemical solutions in compartments below the processing tanks. Flexible, vinyl tubing and numerous fittings are used to interconnect these components and to direct the chemicals solutions to and from the overlying tanks. Positioning of the pumps, heat exchangers, and filters in a compartment beneath the tanks in which the material processing occurs presents a number of problems. The maze of tubing and fittings that are required to interconnect such components can be difficult to access for the periodic maintenance and service that is required. The limited access also makes it difficult to trace the source of a leak in the tubing or fittings to make the necessary repairs.
In addition to the servicing problems presented by such tubing and fittings, purging and cleaning of the tubing, pumps and other components can be very time consuming. This also prevents the ready conversion of the processor between various processes such as color and black and white developing.
Location of the circulation and replenishing pumps, heat exchangers and filter components in a compartment remote from the developing tanks can increase the overall cost as well as the size of the processor. The tubing and fittings that interconnect the processing components can be costly to purchase and install. The size of the circulating pumps must also be increased to compensate for the quantity of chemicals circulated through the tubing, thus further increasing the cost of the processor.
The use of tubing to interconnect the processor components increases the likelihood that an air lock will develop within the circulation systems, such as when changing the filters or servicing any of the various components. If an air-lock should occur, the pump head must be disconnected and bled of air. Liquid will also drain from the pump head and tubing during the bleeding process and will frequently splash onto electrical components within the pump compartment. This liquid spillage can be dangerous in that it may cause an electrical short and may also corrode surrounding components. Placement of a submersible pump directly in the chemical holding tanks reduces the tubing requirements but can still present maintenance and accessibility problems. Moreover, it is generally undesirable from a safety standpoint to locate even a submersible pump within the liquid solution because of the risk of an electrical short circuit should the outer covering on the pump fail.